#include<iostream>
#include<vector>
using namespace std;

int firstMissingPositive(vector<int>& nums) {
    int n = nums.size();
    for (int i = 0; i < n; ++i)
    {
        while (nums[i] > 0 && nums[i] <= n && nums[nums[i] - 1] != nums[i])
        {
            swap(nums[nums[i] - 1], nums[i]);
        }
    }
    for (int i = 0; i < n; ++i)
    {
        if (nums[i] != i + 1)
        {
            return i + 1;
        }
    }
    return n + 1;


}


int main()
{
    vector<int> num1 = { 1,2,0 };
    int sum1 = firstMissingPositive(num1);
    cout << sum1 << endl;
    return 0;
}